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DOE OSTI2025

Simulated Microstructures for Laser Powder Bed Fusion Additive Manufacturing Using Myna, AdditiveFOAM, and ExaCA

This dataset provides sample datasets containing voxelized, three-dimensional representations of simulated grain structures and crystallographic orientations that can result from laser powder bed fusion additive manufacturing. The six microstructure files each contain approximately 1 cubic millimeter of material (1 mm x 1 mm cross-section over 26 simulated layers of deposition). Some of the microstructures have columnar grains that extend across nearly the entire simulation domain, while others have more equiaxed or truncated columnar grains. The process conditions to generate these microstructures were from the Peregrine v2023-10 dataset (10.13139/ORNLNCCS/2008021). The codes used are publicly available and released under open-source licenses. Myna (https://github.com/ORNL-MDF/Myna) was used for configuration of the cases from the Peregrine v2023-10 HDF5 dataset and to run the simulation workflow. AdditiveFOAM (https://github.com/ORNL/AdditiveFOAM) was used to simulate the melt pool and generate solidification conditions. And ExaCA (https://github.com/LLNL/ExaCA ) was used to simulate the three-dimensional microstructures.

36 MATERIALS SCIENCE↗

DOE OSTI2023

An assessment of spall failure modes in laser powder bed fusion fabricated stainless steel 316L with low-volume intentional porosity

Here, this paper reports on spall failure and damage modes in Laser Powder Bed Fusion fabricated Stainless Steel 316L (SS316L) with intentional levels of low-volume (1–5 vol. %) porosity and pore sizes of 200, 350, and 500 μm. The fabricated specimens were subjected to uniaxial-strain plate-impact loading at ~4.5 GPa, to initiate incipient spall failure. Analysis of velocimetry profiles measured using multi-probe photon-Doppler velocimetry coupled with post-mortem analysis of soft-recovered samples reveals local suppression of spall failure (termed as spall-dominated) as a function of porosity, as the failure mechanism transitions from spall-centered tensile stress dominated to a pore-centered microstructure-dominated damage mode involving void/crack nucleation and growth at pre-existing pores. The critical porosity level where the suppression of spall failure is first observed, as well as the spall location, is dependent on both the volume fraction and the size of the initially fabricated pores. In samples of 500 μm pore size, the suppression of spall failure is observed with as little as 1 vol. % porosity, while samples with smaller pores (200 μm) still experience spall-centered tensile stress dominated failure with higher levels (5 vol. %) of porosity. In the case of pore-centered microstructure-dominated failure, spall damage can occur but the spall plane is shifted toward the rear free surface, or more generally in areas further away from the region with pores. Highly heterogeneous deformation twinning, shear banding, grain rotation, and cracking are observed in the vicinity of pre-existing pores and expected spall failure sites.

36 MATERIALS SCIENCE↗

DOE OSTI2023

The role of cellular structure, non-equilibrium eutectic phases and precipitates on quasi-static strengthening mechanisms of as-built AlSi10Mg parts 3D printed via laser powder bed fusion

The quasi-static loading strengthening mechanism in the as-built state of an AlSi10Mg alloy 3D-printed via Laser Powder Bed Fusion (LPBF) was thoroughly identified and quantified using state-of-the-art electron microscopy and synchrotron X-ray diffraction techniques. The yield strength was comprehensively modelled through an in-depth characterization and quantification of the microstructural features as well as their effective volumes for strengthening. In particular, the non-equilibrium eutectic network was characterized with a two-fold structure: cell boundary particles as well as intracellular lamellar/fibrous networks, each consisting of discrete phases exhibiting a thru-thickness compositional gradient, a semi-coherent interface with the matrix and an abundance of crystal defects such as nano-sized sub-grains, microstrains and stacking faults. Further, these altogether made the eutectic phase the most potent contributor to the yield strength accounting for ~30–40% of the estimated value (i.e., cell boundary and eutectic network strengthening combined). Precipitates strengthening was identified as the second most potent mechanism via a shearing process only. Moreover, the presented methodology was able to capture the effect of LPBF processing variables on the individual strengthening contributions, e.g., the effect of a lower laser scanning speed on increasing the cell size as well as the mean precipitate size, which are shown to exhibit opposing impacts on strengthening.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Characterization and Rationalization of Microstructural Evolution in GRCop-84 Processed by Laser-Powder Bed Fusion (L-PBF)

In this study, prismatic geometries of GRCop-84 [Cu-8Cr-4Nb (at. pct)] were built with laser-powder bed fusion (L-PBF) process. The samples were sectioned parallel or perpendicular to the build direction and characterized in the as-built and after post-processing with a hot-isostatically pressing (HIP) treatment. The microstructure and phase evolutions were evaluated with optical microscopy, scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), and high-temperature X-ray diffraction (HTXRD) up to 1223 K. The samples in the as-built conditions exhibited predominantly columnar epitaxial and misoriented Cu-FCC grains. The microstructure evolutions are discussed based on locations within the overall build geometry, the dynamics of small melt pool shape and sectioning effects. The above grain structure did not change significantly during post-process HIP treatment. The stability of this FCC grain structure is attributed to the formation of primary stable Cr 2 Nb (Laves phase) during L-PBF, even before the emergence of FCC grains from liquid. The stability of Cr 2 Nb in both as-built and HIPed samples were evaluated using high-temperature X-ray diffraction measurements and compared with that of gas-atomized powder. The significance of these results is discussed with reference to aerospace applications.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Characterization of Properties of Laser Powder Bed Fusion 3D-Printed Inconel 718 for Centrifugal Turbomachinery Applications

Here, this paper presents the results of a comprehensive effort to characterize the properties of Inconel 718 produced by a form of laser powder bed fusion (LPBF) additive manufacturing (AM) or 3D-printing, subsequently subjected to hot isostatic pressing (HIP) and heat treatment according to standards F3055-14a and AMS 5663, respectively. Material property data, while broadly available for traditional Inconel 718 presentations (e.g. forgings or castings), is currently lacking for the 3D-printed material. It is expected that while limited in size, the experimental data sets presented provide sufficient information to glean the capability of LPBF Inconel 718. These include: 1) Chemical composition, electron backscatter diffraction (EBSD), and x-ray energy dispersive spectroscopy (XEDS) characterization of 3D-printed material structure; 2) Tensile properties — 0.2% yield stress, ultimate stress, modulus of elasticity, and elongation to failure — based on 108 samples, as functions of temperature and sample print orientation; 3) Creep rupture data including the Larson-Miller parameter, based on 21 samples; and 4) High cycle fatigue data based on 21 samples as a function of temperature. Results are compared to available standards and/or data for forged, cast, and other AM Inconel 718. A key observation of this study, based on the EBSD results, is that while the material appears to approach full recrystallization following heat treatment, there is a detectable fraction of the material that does not fully recrystallize, resulting in a material with mechanical properties (e.g. yield stress, creep rupture) measurably lower than those of forgings, but higher than those of castings.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2023

Data-driven prediction of geometry- and toolpath sequence-dependent intra-layer process conditions variations in laser powder bed fusion

Geometrical features and toolpath sequence are two important factors that cause process condition variations, such as variations in the meltpool temperature or meltpool size, that might lead to undesired material properties in the laser powder bed fusion (LPBF) process. Due to the high dynamics and complex physics of the LPBF process, it is difficult to predict variations in process conditions with simulations alone. Advances in measurement technology and computational technologies open up new possibilities for smart manufacturing. In this paper, a data-driven method to predict intra-layer variations in the processing conditions that source from the toolpath sequence and part geometry is presented. The approach is demonstrated using two-color on-axis pyrometer measurements. Three demonstration cases are presented in which it is demonstrated (1) how the trained predictive model can be used as a filter to ease the interpretation of process variations and discover patterns related to toolpath and part geometry, and (2) how to generate predictions that can be used for feedforward control, i.e., for adjusting laser power or scanning speed along the toolpath using a meltpool temperature prediction model generated based on on-axis measurements. Results show that the developed prediction model is able to meaningfully predict process variations resulted from toolpath sequence and geometry. Predictions are aligned with the results from the related work of others and for the case of 180° laser path turnarounds in our high-speed X-ray imaging experiments. In conclusion, the potential issues related to the current maturity status of the process and measuring equipment that could in practice affect the performance of the proposed solutions are also discussed.

42 ENGINEERING↗

DOE OSTI2022

Isothermal and Cyclic Oxidation of Haynes 282 Processed by Electron Beam Melting (EBM) and Laser Powder Bed Fusion (LPBF) in Dry Air at 800 and 950°C

Here, the isothermal and cyclic oxidation behavior of Haynes 282 (H282) processed by laser powder bed fusion and electron beam melting was compared to its cast counterpart during exposures in air at 800 and 950°C. The specific microstructure of the AM alloys compared to coarse-grain cast 282 resulted in differences in oxidation rates, internal oxidation and spallation behavior. At 800°C, faster Ti diffusion to the surface due to the smaller grain size of the AM alloys led to Ti doping of the Cr 2 O 3 scale and faster oxidation rates. The higher density of grain boundaries also resulted in more pronounced internal oxidation. At 950°C, a duplex Cr 2 O 3 scale was observed with a dense inner layer and porous cracked outer layer with embedded TiO 2 particles. The impact of the external and internal oxide compositions and oxidation-induced elemental depletions on the oxidation lifetime, creep properties and spallation behavior is discussed.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Leveraging Solute Segregation in Laser Powder Bed Fusion to Achieve Superior Strength and Ductility Via Single-Step Heat Treatment in Ti-Free Grade 300 Maraging Steel

Maraging steels are Fe-Ni precipitation-strengthened steels that can be heat treated for achieving high strength with an accompanying loss in ductility, a trend common to most metals. Here, we show that the segregation of Ni during laser powder bed fusion, commonly considered a nuisance that is dealt with via solutionizing heat treatments, can be leveraged via direct aging to achieve higher strength and ductility simultaneously, compared to a solutionized and aged condition. The high dislocation density in combination with solute segregation in the as-fabricated material promotes the precipitation of Mo-rich intermetallic phases that are responsible for the high strength, and the Ni segregated regions facilitate austenite reversion during direct aging. The reverted austenite enhances the elongation via transformation-induced plasticity. While overcoming the strength–ductility conundrum, direct aging can significantly reduce the energy and emissions associated with multistep heat treatments, especially in the global tool and die industry, while laser powder bed fusion (LPBF) can enable tools with integrated cooling channels for increased downstream production efficiency.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Process optimization of complex geometries using feed forward control for laser powder bed fusion additive manufacturing

Additive manufacturing (AM) enables the fabrication of complex designs that are difficult to create by other means. Metal parts manufactured by laser powder bed fusion (LPBF) can incorporate intricate design features and demonstrate desirable mechanical properties. However, printing a part that is qualified for its intended application often involves reprinting and discarding many parts to eliminate defects, improve dimensional accuracy, and increase repeatability. The process of iteratively converging on the appropriate build parameters increases the time and cost of creating functional LPBF manufactured parts. This work describes a fast, scalable method for part-scale process optimization of arbitrary geometries. Additionally, the computational approach uses feature extraction to identify scan vectors in need of parameter adaptation and applies results from simulation-based feed forward control models. This method provides a framework to quickly optimize complex parts through the targeted application of models with a range of fidelity and by automating the transfer of optimization strategies to new part designs. The computational approach and algorithmic framework are described, a software package is implemented, the method is applied to parts with complex features, and parts are printed on a customized open architecture LPBF machine.

3D printing↗

DOE OSTI2023

A Co-Registered In-Situ and Ex-Situ Tensile Properties Dataset from a Laser Powder Bed Fusion Additive Manufacturing Process (Peregrine v2023-11)

This release contains a co-registered in-situ and ex-situ Peregrine dataset from five Concept Laser M2 Laser Powder Bed Fusion (L-PBF) stainless steel 316L builds containing 6,299 SS-J3 individually tracked tensile coupons. These data were collected at the Manufacturing Demonstration Facility (MDF) located at Oak Ridge National Laboratory (ORNL). The dataset includes layer-wise visible-light in-situ imaging data, the laser scan paths and parameters, in-situ temporal sensor data, room-temperature static tensile test results, and the target part geometries. Additionally, anomaly detections produced by a modified Dynamic Segmentation Convolutional Neural Network (DSCNN) are provided.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Laser powder bed fusion of ODS Fe–Cr–Al (0.3Zr, 0.3Y 2 O 3 ): Unveiling processing-microstructure- mechanical property relationships

Here, this study investigates the fabrication of oxide dispersion strengthened (ODS) Fe-Cr-Al alloys via laser powder bed fusion (LPBF) with strategic additions of 0.3 wt% Zr and 0.3 wt% Y 2 O 3 for enhanced mechanical performance in nuclear applications. Systematic processing parameter optimization yielded three distinct conditions: one low-density product with significant defects and two near-full-density materials with improved consolidation. Comprehensive characterization confirmed single-phase α-ferrite matrix formation with successful incorporation of Y-, Zr-, O-, and C-rich precipitates characteristic of ODS alloys. However, precipitate density remained low (∼10 7 cm −3 ), resulting in sink strength values substantially below optimal levels for radiation resistance. Microhardness values (mid-200s HV) correlated inversely with grain size following the Hall-Petch relationship, indicating grain boundary strengthening as the dominant mechanism rather than precipitation strengthening. The optimized processing conditions achieved excellent mechanical properties with room temperature yield strength of approximately 500 MPa and 30 % elongation, demonstrating superior strength-ductility synergy compared to other additively manufactured ODS materials and performance consistent with literature values for LPBF-processed ODS-FeCrAl alloys. This investigation reveals both the potential and limitations of LPBF processing for ODS Fe-Cr-Al alloys. While successful defect-free fabrication was achieved, results highlight the critical need for systematic optimization of processing parameters and post-processing heat treatments to enhance precipitate density for effective dispersion strengthening and radiation resistance while maintaining additive manufacturing advantages.

Additive manufacturing↗

DOE OSTI2020

Oxide dispersion strengthened 304 L stainless steel produced by ink jetting and laser powder bed fusion

This paper discusses the fundamentals of a novel hybrid method to synthesize oxide dispersion strengthened (ODS) 304 L stainless steel (SS) alloy using a modified laser powder bed fusion (LPBF) machine. Previously, ODS metal matrix composites have been produced by LPBF via ball-milling, which is expensive to scale. Here, we selectively dope yttria nanoparticles into a SS matrix by jetting a precursor chemistry onto the SS substrate prior to laser conversion and consolidation. Here, the new alloy shows good room temperature mechanical properties. Microstructures are studied using electron microscopy, energy dispersive spectroscopy and electron backscatter diffraction.

36 MATERIALS SCIENCE↗

DOE OSTI2023

A Co-Registered In-Situ and Ex-Situ Dataset from a Laser Powder Bed Fusion Additive Manufacturing Process (Peregrine v2023-10)

This release contains a co-registered in-situ and ex-situ Peregrine dataset from a single Concept Laser M2 Laser Powder Bed Fusion (L-PBF) stainless steel 316L build. These data were collected at the Manufacturing Demonstration Facility (MDF) located at Oak Ridge National Laboratory (ORNL). The dataset includes layer-wise visible-light in-situ imaging data, the laser scan paths and parameters, in-situ temporal sensor data, X-Ray Computed Tomography (X-CT) scans, pycnometry and tensile test results, etched micrographs from selected locations, and the target part geometries. Additionally, anomaly detections produced by a modified Dynamic Segmentation Convolutional Neural Network (DSCNN) are provided.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Effect of heat treatment on creep behavior of 316 L stainless steel manufactured by laser powder bed fusion

The objective of this study is to understand the thermal stability of microstructure and its effect on the creep behavior of additively-manufactured 316L stainless steel (AM 316L SS). Creep specimens were fabricated from rods printed by a laser powder bed fusion process. Six different heat treatments, namely 650 °C/1 h, 700 °C/1 h, 750 °C/1 h, 800 °C/1 h, 900 °C/1 h and 1050 °C/1 h were applied to the creep specimens. The heat-treated specimens were creep-tested under the same condition, 550 °C/275 MPa to evaluate the effect of post-build heat treatment on the creep behavior of AM 316L SS. In the temperature range of 650-750 °C, dislocation density within cells, and cell size and wall thickness were affected by the heat treatment, while elemental segregation at boundaries remained unchanged and Mn-enriched Si oxide particles remained stable. In the temperature range of 750-900 °C, concurrent changes were observed in dislocation cell structures, elemental segregation and oxide particles. The 1050 °C-heat treatment removed cell structures and boundary solute segregations, leading to formation of equiaxed grains; Mn-enriched Si oxide particles in the as-built specimen were replaced by more stable Mn-enriched Cr oxides. The creep life of AM 316L SS increased after the heat treatment at 650 °C and then decreased with increasing temperature up to 900 °C where cell/subgrain structures still existed. The creep rate and creep elongation followed an opposite trend. The creep rate can be correlated with the structural parameters of cell/subgrain size and cell wall/boundary thickness and can be rationalized by different strengthening mechanisms of dislocation cells and subgrains. The heat treatment affected strongly the primary and secondary creep but had a minimal effect on the tertiary creep of AM 316L SS.

316L stainless steel↗

DOE OSTI2024

Laser powder bed fusion of oxide dispersion-strengthened IN718 alloys: A complementary study on microstructure and mechanical properties

In this study, two new grades of oxide dispersion strengthened (ODS) Inconel 718 (IN718) alloys were designed by the thermochemical CALPHAD method and produced by laser powder bed fusion (LPBF) technique. Alloys designated as IN718-YF and IN718-YFH, that consist Y 2 O 3 –FeO and Y 2 O 3 –FeO–Hf, respectively, were fabricated with >99.9 % densification using optimized process parameters. CALPHAD calculations were highly consistent with experimental findings, highlighting the formation of Al-containing Y–Ti–O and Y–Hf–O nano-oxides in both alloy types. Texture analyzes revealed no significant texture development in as-built (AB) or heat-treated (HT) alloys. Heat treatment was applied at 1050 °C for 1 h to enhance nano-oxide density. Further, the nano-oxide number density remained similar in IN718-YF while it decreased in IN718-YFH alloy as a result of carbide formation after the heat treatment. Besides, formation of secondary γ' particles was observed in the IN718-YFH/HT alloy. Even though the yield strengths of IN718-YF and IN718-YFH alloys in both AB and HT conditions were similar, the ductility of IN718-YFH was ~50 % less in almost all conditions compared to the ductility of IN718-YF. This has been shown to be as a result of irregular shaped micron-sized Y-Hf-O oxides, martensite formation in AB condition, increased amount of carbides and existence of secondary γ' particles in HT condition in IN718-YFH. High density of stacking faults (SF) forming at the interface of the nano-oxides have been detected in IN718-YF alloys. Besides dislocation/nanoparticle interactions, SFs which are responsible for the delocalization of the deformation improve the ductility of IN718-YF alloys. Overall, high temperature mechanical tests exhibit that both alloys have higher strength with improved ductility compared to the standard IN718 alloys, indicating the contribution of the nano-oxides.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Melt-Pool Dynamics and Microstructure of Mg Alloy WE43 under Laser Powder Bed Fusion Additive Manufacturing Conditions

Magnesium-based alloy WE43 is a state-of-the-art bioresorbable metallic implant material. There is a need for implants with both complex geometries to match the mechanical properties of bone and refined microstructure for controlled resorption. Additive manufacturing (AM) using laser powder bed fusion (LPBF) presents a viable fabrication method for implant applications, as it offers near-net-shape geometrical control, allows for geometry customization based on an individual patient, and fast cooling rates to achieve a refined microstructure. In this study, the laser–alloy interaction is investigated over a range of LPBF-relevant processing conditions to reveal melt-pool dynamics, pore formation, and the microstructure of laser-melted WE43. In situ X-ray imaging reveals distinct laser-induced vapor depression morphology regimes, with minimal pore formation at laser-scan speeds greater than 500 mm/s. Optical and electron microscopy of cross-sectioned laser tracks reveal three distinct microstructural regimes that can be controlled by adjusting laser-scan parameters: columnar, dendritic, and banded microstructures. These regimes are consistent with those predicted by the analytic solidification theory for conduction-mode welding, but not for keyhole-mode tracks. The results provide insight into the fundamental laser–material interactions of the WE43 alloy under AM-processing conditions and are critical for the successful implementation of LPBF-produced WE43 parts in biomedical applications.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Machine learning–aided real-time detection of keyhole pore generation in laser powder bed fusion

Porosity defects are currently a major factor that hinders the widespread adoption of laser-based metal additive manufacturing technologies. One common porosity occurs when an unstable vapor depression zone (keyhole) forms because of excess laser energy input. With simultaneous high-speed synchrotron x-ray imaging and thermal imaging, coupled with multiphysics simulations, we discovered two types of keyhole oscillation in laser powder bed fusion of Ti-6Al-4V. Amplifying this understanding with machine learning, we developed an approach for detecting the stochastic keyhole porosity generation events with submillisecond temporal resolution and near-perfect prediction rate. Finally, the highly accurate data labeling enabled by operando x-ray imaging allowed us to demonstrate a facile and practical way to adopt our approach in commercial systems.

42 ENGINEERING↗

DOE OSTI2021

Investigation of Mechanical Properties of Parts Fabricated with Gas- and Water-Atomized 304L Stainless Steel Powder in the Laser Powder Bed Fusion Process

In this report the use of gas-atomized powder as the feedstock material for the Laser Powder Bed Fusion (L-PBF) process is common in the Additive Manufacturing (AM) community. Although gas-atomization produces powder with high sphericity, its relatively expensive production cost is a downside for application in AM processes. Water atomization of powder may overcome this limitation due to its low cost relative to the gas-atomization process. In this work, gas- and water-atomized 304L stainless steel powders were morphologically characterized through Scanning Electron Microscopy (SEM). The water-atomized powder had a wider particle size distribution and exhibited less sphericity. Measuring powder flowability using the Revolution Powder Analyzer (RPA) indicated that the water-atomized powder had less flowablility than the gas-atomized powder. Through examining the mechanical properties of L-PBF fabricated parts using tensile tests, the gas-atomized powder had significantly higher yield tensile strength and elongation than the water-atomized powder, however, their ultimate tensile strengths were not significantly different.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗